Macrophage-Colony Stimulating Factor （M-CSF）, also known as Colony Stimulating Factor-1 （CSF-1）, is a hematopoietic growth factor. It can stimulate the survival, proliferation and differentiation of mononuclear phagocytes, in addition to the spreading and motility of macrophages. M-CSF is mainly produced by monocytes, macrophages, fibroblasts, and endothelial cells. M-CSF interaction with its receptor, c-fms, has been implicated in the growth, invasion, and metastasis of several diseases, including breast and endometrial cancers. The biological activity of human M-CSF is only active in the disulfide-linked dimeric form, which is bonded at Cys63.